A test-scoring machine is known to record an incorrect grade on 5% of the exams it grades.

Question:

A test-scoring machine is known to record an incorrect grade on 5% of the exams it grades. Find, by the appropriate method, the probability that the machine records
a. exactly 3 wrong grades in a set of 5 exams.
b. no more than 3 wrong grades in a set of 5 exams.
c. no more than 3 wrong grades in a set of 15 exams.
d. no more than 3 wrong grades in a set of 150 exams.